Dewatering screen



Dec. 2l, 1948. J. w. WANTLING 2,457,018

DE-WATERING SCREEN 2 Sheets-Sheet l Filed Dec. 16 1944 lNVENTORATTORNEYS Dec. 21, 1948. J. w. wANTLlNG 2,457,018

DE-WATERING SCREEN I' Filed Deo. 1e, 1944 2 shawls-sheet 2 Jose/v W 5%,zal TTRNEYS Patented Dec. l21, 1948 DEWATERING SCREEN Joseph W.Wantling, Allwood, N. J., assigner, by

mesne assignments, to Hewitt-Robins Incorporated, a corporation oi' NewYork Application December 18, 1944, Serial No. 568,432

8 Claims.

This invention relates to screens of the kind used for the de-wateringof coal and the wet screening of anthracite and bituminous sludge.

The principal object of the invention is a screen of greatly increasedefficiency, particularly with regard to the amount of water removed fromthe material following the washing operation. The invention will beclearly understood from the en. suing description and accompanyingdrawings, from which other objects and advantages and particularfeatures of the invention will also be apparent.

In the drawings, Fig. l is a broken-out, partially diagrammatic, planview of a screen embodyingithe invention; Fig. 2 is a vertical sectionon the line II-II of Fig. l; Fig. 3 is a much enlarged plan view of aportion of the screen of Fig. 1, with parts omitted; Fig. 4 is avertical section approximately on the line IV-IV of Fig. 3; and Fig. 5is a transverse vertical section, as on the line V--V of Fig. 3.

Screens of the kind referred to and to which the invention is applicableare comprised essentially of an elongated, foraminous deck adapted to bebodily vibrated to screen the coal horizontal, frequently oi about 45.Usually, also,

such screens are themselves set at a slight angle to the horizontal,say. of the order of 2 or 3 degrees, so that the material being screenedprogresses slightly' upgrade.

In the preferred form shown for purposes of illustration, the screencomprises a deck, generally designated i, composed of a series ofclosely spaced bars, generally designated 2, extending longitudinally ofthe deck and supported and welded to cross-bars 3. As will beunderstood, the bars 2 are dimensioned and spaced appropriately for theparticular material to be handled; for example, where itis desired towash and screen out dust and fine particle size material. the bars 2 maybe of a diameter of about of an inch and their normal spacing abouta/ioon of an inch. As shown in Fig. 2, the deck is set at a slight angleto the horizontal, nthe material being supplied to it at the right-handend as viewed inthis figure and discharged .from the left-hand end. Thescreen may be bodily vibrated, say, at an angle of 45 to the horizontalas indicated by the arrow V and at a speed of the order of one thousandor more vibrations per minute.

Such washing of the material as takes place during the screening iseffected during, say, the first half of the travel oi the material overthe deck and for this purpose there may be mounted above the screen aseries of transversely extending water-spray pipes l, as shown in Figs land 2.

According to the present invention the upper surface of the screen isprovided at spaced intervals with transversely extending baffles adaptedto intercept the material as it progresses along the screen and soarranged as to overhang a portion of the deck surface on the far side ofthe baflies; that is to say. on the side toward which the material ismoving. The effect of such baffles is to maintain on the far side ofeach of them and immediately adjacent the baffles a short transversestrip of screen surface substantially free oi the material beingscreened. That is to say, by reason of the overhanging form of thebailies, they serve as a sort of shield. In the result, a considerableamount of water can and does pass freely through the screen at thesepoints, the flow of such water into the clear space adjacent the bailiesbeing accentuated by the in. eline of the deck as a whole.

In this illustrated preferred form each of the overhanging bafescomprises a transversely mounted plate 5 welded or otherwise secured toand upstanding from. the screen surface and canted forwardly withrespect to the direction of movement of the material being screened. Asthe result of this overhanglng baffle arrangement. the material assumesa form similar to that indicated in Fig. 2, piling up behind the bailiesas indicated at 6, and spread out as at 1 in a relatively thin layerextending rearwardly toward but terminating short of the previousbaille. It has been found that the width of the clear space on the farside of each baflie is appreciably greater than the actual overhang oithe baille.

In order further to facilitate the escape of water from the material, atransverse trough-like depression is formed in the deck adjacent thelongitudinal screen bars throughouta short portion of its length,twosuch bars specifically designated I and I0 being shown in thisfigure.

It will be recognized that the maintenance of the material-free spaceyon the 'far side of each baille 8 makes it feasible to increase thescreen openings in this space and thereby accelerate the escape of thewater; and this result' is conveniently accomplished in the form ofscreen illustrated by spreading as well as depressing the longitudinalscreen bars in the formation of the trough-like depressions 8. As shownin Figs. 3, 4 and 5, every third bar 9 is deformed by being simplydownwardly curved or depressed, whereas the intervening bars I -areoEset laterally as well as being depressed downwardly. As the result ofthis arrangement, the longitudinal screen bars in each depression 8 takethe form shown in Figs. 3 and 5, providing screen openings il of verysubstantially greater spacing than the spacing of the bars throughoutthe remainder of the screen.

While all the reasons for the phenomenon are not entirely understood, ithas been found to be Ifeasible and advantageous to provide a similartrough-like depression by a second transverse series of bar deformationsimmediately ahead of, say, the last baille, as shown at l2 in Figs, 1and 2. By the time the material has progressed to this point on thedeck, it is, of course, much drier than when it encounters the firstbaille and it exhibits a tendency to cohere. Also, it appears to partakeof a rolling motion as it moves up and over the last baile and losesstill more water in the process. The escape of this water, by way ofpositely deformed to Ibring certain of the trough portions of the barscloser together into groups, the groups thereby also being more widelyspaced from each other than the adjacent straight portions of the bars,a'transverse baille plate upstandlng from the deck at the entrance sideof each trough and canted forwardly, with respect to the direction ofmovement of the material heilig screened, to overhang its adjacenttrough, one of said troughs and baiiles being located near the dischargeend of the screen, and a supplenientary, similar trough locatedimmediately ahead of said last-mentioned baille.

3. A cie-watering screen deck comprising a series of closely spaced,straight bars running lengthwise of the deck, said bars having, atintervals throughout their length, transversely aligned short lengthsthereof downwardly depressed to form spaced shallow troughs extendingtransversely across the deck, the depressed portions of certain of thebars being laterally and oppositely deformed to bring certain of thetrough portions the trough i2, is found not to be accompanied by anysubstantial loss oi material in spite ofthe wider spacing of .the barsin this trough.

The foregoing features result in a highly eifective screening operation,and notwithstanding the washing which takes place throughout the initialstages, the water content of the discharged material is extremely low.

While the foregoing constitutes a detailed description of the preferredform, it will be understood that various modifications may be resortedto within the scope of the invention as defined by the following claims.

I claim:

l. A screen deck comprising a series of closely spaced, straight barsrunning lengthwise of the deck to provide a washing section followed bya de-waterlng section, said bars having, at intervals throughout thelength of the de-watering section only, transversely aligned shortlengths thereof downwardly depressed to form spaced shallow troughsextending transversely across the deck, the depressed portions ofcertain of the bars being laterally and oppositely deformed to bringcertain of the trough portions of the bars closer together into groups,the groups thereby also be ing more widely spaced from each other thanthe adjacent straight portions of the bars, a. transverse baille plateupstandlng from the deck at the entrance side of each trough and cantedforwardly, with respect to the direction of movement of the materialbeing screened, to overhang its adjacent trough, one of said troughs andbafiies being located near the discharge end of the screen, and asupplementary, similar trough located immediately ahead of saidlast-mentioned baille.

2. A de.watering screen deck comprising a series of closely spaced,straight bars running lengthwise of the deck, said bars having,at'intervals throughout their length, transversely aligned short lengthsthereof downwardly depressed' to form spaced shallow troughs extendingtransversely across the deck, the depressed portions of certain of thebars being laterally and op- 76- of the bars closer together intogroups, the groups thereby also being more widely spaced from each otherthan the adjacent straight portions of the bars, and a transverse bailleplate upstandlng from the deck at the entrance side of each trough 'andcanted forwardly, with respect to the direction of movement of thematerial being screened, to overhang its adjacent trough.

d. A de-watering screen deck comprising a series of closely spaced,straight bars running lengthwise of the deck, said bars having, atintervals throughout their length, transversely aligned short lengthsthereofdownwardly depressed to form spaced shallow troughs extendingtransversely across the deck, the depressed portions of certain adjacentbars being more widely spaced from each other than the adjacent straightportions of such bars, and a transverse baille plate upstandlng from thedeck at the entrance side of each trough and canted forwardly, withrespect to the direction of movement of the material being screened, tooverhang its adjacent trough to an extent sufficient to maintain suchtrough substantially free of solid material.

5. A screen deck adapted to be upwardly canted with respect to thedirection of movement'thereon direction of movement of the materialbeing screened, to overhang its adjacent trough to an extent suiiicientto maintain such trough substantially free of solid material.

6. A de-watering screen deck comprising a series of closely spaced,straight bars running lengthwise of the deck, said bars having, atintervals throughout their length, transversely aligned short lengthsthereof downwardly depressed to form spaced shallow. open-topped troughsex-` tending transversely across the deckI and a transverse baille plateupstandlng from the deck at the entrance side of each trough, each such`baille plate being canted forwardly, with respect to the direction ofmovement or the material being screened to overhang its adjacent troughto an extent sufcient to maintain such trough substantially free ofsolid material.

'7. In a de-watering screen comprising a at, foraminous.material-supporting deck adapted to be tilted upwardly with respect tothe direction of travel of material thereon and to be vibrated toadvance a layer of wet, solid material longitudinally of the deck: saiddeck surface being bodily deformed at intervals to form transverselyextending, shallow, trough-like depressions, each said depressionmerging into and having free surface communication with the\deck surfaceon the exit sides of the depressionswith respect to the direction ofmovement of thematerial, thereby permitting free gravity flow of liquidinto the said exit sides of the depressions from the adjacent decksurface, and upstanding baille means on the deck surface adjacent theentrance side of each depression, each said baille means adapted tooverhang its adjacent depression to an extent suilicient to maintain itssub'- stantially free of solid material.

8. In a de-watering screen comprising a foraminous, material-supportingdeck adapted to be vibrated to advance a layer of wet, solid materiallongitudinally of the deck: said deck having a series of transverselyextending, shallow, spaced troughs each in free surface communicationwith the adjacent deck surface on the exit sides of the troughs withrespect to thedirection of movement of the material, thereby permittingfree, gravity-flow of liquid into the said exit sides. of the troughsfrom the adjacent deck surface, and upstanding baille means on the decksurface adjacent the entrance side of each trough adapted to maintaineach said trough substantially free of solid material.

JOSEPH W. WANTLING.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 256,315 Graves et al.v Apr. 11,1882 538,794 Rockteschel May 7, 1895 2,089,676 Ulrich Aug. 10, 19372,150,889 Colville Mar. 14, 1939 2,308,572 Symons l. Jan. 19, 1943FOREIGN PATENTS Number Country Date 12,692 Great Britain Aug. 12, 1889618,152 Germany Sept. 2, 1935 641,741 Germany Feb. 11, 1937

